1. Field of the Invention
The present invention relates to a bending operation apparatus of an endoscope including a bendable bending portion, and the endoscope.
2. Description of the Related Art
An endoscope including a bending portion configured to direct a distal end portion of an insertion section to a desired direction is widely used as an endoscope to perform observation, various treatments and the like by having an elongated insertion section inserted into a living body or the like. Generally, this type of endoscope has an operation section consecutively provided on a proximal portion side of the insertion section, and an operation of bending the bending portion is performed through a bending operation apparatus provided in the operation section.
As the bending operation apparatus, a structure which is configured to bend the bending portion by pulling or slackening an operation wire connected to the bending portion is widely used, and in this case, a rotating member such as a pulley or a sprocket is generally used to pull or slacken the operation wire.
Furthermore, generally, this type of bending operation apparatus is provided with a lock mechanism configured to restrict (brake) rotation of the rotating member with a predetermined amount of fixing force, and to fix (lock) the bending portion in a desired bent state. For example, Japanese Patent Application Laid-Open Publication No. 2008-23064 discloses a bending operation apparatus according to which, when a lock operation shaft is rotated around the shaft, a locking plate is eccentrically rotated to perform braking by coming into contact with and moving away from the outer circumferential surface of a pulley drive shaft.
A conventional lock mechanism as disclosed in Japanese Patent Application Laid-Open Publication No. 2008-23064 is configured to slow the operation of the pulley by pressing a friction member such as the locking plate against the pulley drive shaft to thereby lock a bending portion.